[taneq]

It has to be more than just "is aware of harmful effects but continues to use", otherwise anyone who is aware of the existence of hangovers (or other negative effects) but continues to drink alcohol is "abusing" it.

It would have to be something like "the person using the substance doesn't feel that the positive effects are worth the negative effects but they still cannot stop using it."

[DanBC]

Yes, sorry, "is aware that harm is caused but continues to use".

BTW if people are drinking alcohol and regularly (once a month) getting hangovers they're absuing alcohol.

[taneq]

Oh, I thought that's what it was for. :P